1. Field of the Invention
The present invention relates to a battery pack which is formed so that it can be attached to and detached from an electronic apparatus and in which battery cells for supplying driving electric power to the apparatus main body is contained.
2. Description of the Related Art
As portable electronic apparatuses such as digital still cameras and camcorders, there have widely been used those which are provided with a battery mounting portion such that a battery pack loaded with battery cells is attached thereto and detached therefrom by the user himself. At the time of using such an apparatus, a previously charged battery pack is attached to the battery mounting portion, and, when the battery has run down, the battery is replaced with a separately charged spare battery pack, whereby the apparatus can be used for a long time.
In addition, the lithium ion secondary batteries used for portable electronic apparatuses in recent years include those for which the smart battery specification is adopted as a specification for specifying the management of data between the electronic apparatus and the battery pack and the charger and which include data communication terminals conforming to the SMBus (System Management Bus) communication protocol, in addition to positive and negative electrode terminals. In this kind of battery pack, a smart battery standard IC is mounted, and the residual battery capacity, i.e., how long the battery can be used more, is computed based on such data as temperature characteristics, cycle characteristics, etc. of battery cells incorporated in the battery pack and the environment and history of use of the battery pack, and is communicated to the electronic apparatus side. Further, in order to cope with pirated products, there has been proposed a system in which ID information indicating that the battery pack mounted in position is a genuine product and the like are transmitted to the electronic apparatus, and the battery in question is accepted on the electronic apparatus side only when the battery pack is certified as a genuine product.
It is convenient to arrange such communication terminals side by side with the electrode terminals at a face of the battery pack, from the viewpoints of attachment and detachment of the battery pack to and from the battery mounting portion as well as the configurations of the battery pack and the battery mounting portion. However, where the communication terminals are arranged side by side with the electrode terminals, electromagnetic radiation from the electrode terminals or electrode tabs connected to the battery cells may influence heavily or hamper the accurate data communication.
Each of this kind of battery packs is provided with terminal portions corresponding to electrode terminals disposed on the battery mounting portion side, and is attached to the battery mounting portion in such a manner that the terminal portions are mated to the electrode terminals. Here, in business-use camcorder and the like, the battery capacity required is higher, the battery cells incorporated therein are hence larger and the battery pack is larger in size and weight, since the use time is longer and the use frequency is higher, as compared with private-use camcorders and the like. In the business-use camcorders and the like, therefore, the loads exerted on the engaging members provided between the battery pack and the battery mounting portion to which the battery pack is attached have been increasing, and, when vibration is generated on the apparatus main body side during use, excessive loads would be exerted on the engaging members. Therefore, the engaging members formed in the battery mounting portion and the battery pack are enlarged in size in order to be enhanced in strength.
Meanwhile, of the battery packs, those ones in which lithium ion batteries are used have, incorporated therein, a circuit board including a protective circuit for stopping charging upon overcharge, for stopping discharging upon over-discharge, for stopping a large-current discharge such as an external short-circuit and for the like purposes. When an engaging portion formed in a battery pack is enlarged in size, the engaging portion protrudes largely to the inner side, so that the circuit board disposing region would be narrowed, restrictions would be imposed on mounting regions or patterning regions for circuit elements, and the degree of freedom in designing the circuit board would be spoiled. In addition, if the circuit board is disposed while avoiding the engaging portion, the battery pack would be enlarged in size accordingly, and a dead space would be generated between the circuit board and the battery pack.
Further, this kind of battery pack is provided at one surface thereof with terminal portions to be joined to electrode terminals formed at a battery mounting portion of an electronic apparatus. Electrode tabs which are connected to battery cells contained in the battery pack and electrode members which are connected to the electrode tabs and to which the electrode terminals on the battery mounting portion side are joined, are disposed at the terminal portions. The electrode member includes a terminal plate, a metallic bearing or the like according to the shape of the electrode terminal on the battery mounting portion side. In the battery pack, the one surface is provided with a recessed surface portion, and end faces of the electrode members are exposed from a bottom surface of the recessed surface portion, whereby the electrode members are prevented from short-circuiting or being broken.
However, disposing the electrode members at the bottom surface of the recessed surface portion has been found unsatisfactory for preventing the electrode members from short-circuiting or being broken. Besides, in the case where the electrode member is configured as a metallic bearing, the insertion of terminal pins constituting the electrode terminals on the battery mounting portion side into opening ends of the metallic bearings exposed from the bottom surface of the recessed surface portion could not be smoothly carried out, due to interference of the terminal pins with the bottom surface or the like.
Still further, if the residual capacities of batteries can be checked at the time of loading or replacing a battery pack, it is possible to select a spare battery pack with more residual capacity from among a plurality of spare battery packs and to discriminate the spare battery pack with more residual capacity from already exhausted battery packs, which is convenient. However, where there are a plurality of spare battery packs, it is time consuming to confirm the residual capacities of the battery packs one by one. Therefore, it has been desired that the residual capacities of a plurality of spare battery packs can be checked collectively, in the case where speedy battery replacement is necessary, such as during shooting.
In addition, a battery pack of the type in which the residual battery capacity is displayed with light emitting elements turned ON has the problem that the visibility of the residual battery capacity display would be lowered outdoors in a fine weather or in a light-illuminated place. On the other hand, a residual capacity display method in which the light emitting elements are normally turned ON at a high luminance consumes a considerable amount of electric power and is uneconomic.
Still further, this type of battery packs are each provided with terminal portions corresponding to electrode terminals disposed on the battery mounting portion side, and need to be mounted to the battery mounting portion so that the electrode terminals are mated with the terminal portions. In this kind of electronic apparatuses, therefore, various mechanisms for preventing mis-mounting of battery pack are adopted, such as a mechanism in which the battery pack cannot be inserted into the battery mounting portion if the battery pack is about to be inserted in a wrong mounting direction and a mechanism in which the battery pack cannot be inserted to the depth of the battery mounting portion in such a situation.
However, all of these methods have problems as follows. Whether or not the mounting direction is right cannot be judged unless it is once tried to insert the battery pack into the battery mounting portion. Therefore, in order to mount the battery pack correctly, it would be necessary to visually check the orientation of the battery pack before mounting.
However, in the case where replacement of battery pack is necessary during use of a digital still camera or a camcorder, there is often little time to visually confirm the orientation of the battery pack. Besides, the electronic apparatus is not necessarily used in a light place, and it may be difficult to visually check the orientation of the battery pack in relation to the battery mounting portion.
Meanwhile, it is convenient that the loading/unloading direction of the one surface provided with the terminal portions in relation to the surface provided with the electrode terminals on the battery mounting portion side can be judged intuitively without needing visual confirmation. In general, however, this kind of battery pack is substantially rectangular in shape, and the electrode terminals are not exposed to the outside, so that it is difficult, by relying on the outside shape only, to check the loading/unloading direction of the battery pack in relation to the battery mounting portion.
Furthermore, in business-use camcorders and the like, the use time is longer and the use frequency is higher, so that the battery capacity required would be higher, as compared with private-use camcorders and the like. Accordingly, the battery packs for business-use camcorders and the like are enlarged in size and weight, which may lead to accidental dropping of the battery pack at the time of replacement thereof.
Still further, each of this kind of battery packs is provided with terminal portions corresponding to electrode terminals disposed on the battery mounting portion side, and is attached to the battery mounting portion in such a manner that the terminal portions are mated to the electrode terminals. Here, in business-use camcorders and the like, the battery capacity required is higher and the battery pack is hence larger in size and weight, since the use time is longer and the use frequency is higher, as compared with private-use camcorders and the like. In the business-use camcorders and the like, therefore, if chattering is present between the battery pack and the battery mounting portion to which the battery pack is mounted, the loads exerted on the battery pack and the battery mounting portion due to vibrations on the apparatus main body side during use would be high.
On the other hand, in the case where a recess shape for contriving engagement with a protrusion shape projectingly provided at the battery mounting portion is formed in a large size in a mount surface, for mounting to the battery mounting portion, of the battery pack in order to prevent the chattering, the identification label adhering region of the mount surface would be narrowed, and the size of the circuit board disposed on the inner surface side of the mount surface and an electronic part mounting region would be limited.
[Patent Document 1]
Japanese Patent Laid-open No. Hei 9-243718
[Patent Document 2]
Japanese Patent Application No. Hei 10-144195
[Patent Document 3]
Japanese Patent Laid-open No. Hei 10-312782
[Patent Document 4]
Japanese Patent Laid-open No. Hei 5-101852
[Patent Document 5]
Japanese Patent Laid-open No. 2002-124223
[Patent Document 6]
Japanese Patent Laid-open No. 2006-228471